Recently, with the development and wide application of electronic products, such as mobile phones, PDAs, and notebook computers, there have been increasing demand for flat display elements which consume less electric power and occupy less space. Organic electroluminescent devices are self-emitting and highly luminous, with wide viewing angles, fast response speeds, and simple fabrication methods, making them an industry display of choice.
Generally, an organic electroluminescent device is composed of a light-emission layer sandwiched between a pair of electrodes. When an electric field is applied to the electrodes, the cathode injects electrons into the light-emission layer and the anode injects holes into the light-emission layer. When the electrons recombine with the holes in the light-emission layer, excitons are formed. Recombination of the electron and the hole results in light emission.
An OLED is typically categorized into a micro-molecular and high-molecular OLED according to the substrate type thereof. A micro-molecular substrate OLED is generally fabricated by way of vacuum evaporation, such that the micro-molecular materials have a good film forming quality. However, 95% of the organic electroluminescent materials are deposited on the chamber wall of the manufacturing equipment used to manufacture the OLED, such that only 5% of the organic electroluminescent materials are coated on a substrate after the manufacturing process is completed.
A wet process (such as spin coating or blade coating) has been provided to fabricate micro-molecular OLEDs to improve the utilization ratio of organic electroluminescent materials Therefore, it is necessary to develop novel organic compounds suitable for use in a wet process to fabricate phosphorescent OLEDs to solve the above problems.